Month: August 2025

TRIP MULTIPLY

The most common use of this function is to prevent unwanted monitor alarms during certain

conditions of machine operation. In the operation of some machinery, it is impossible to avoid

some periods of “higher than normal” vibration. Examples include startup and coastdown,

especially if the operating speed is above rotor system balance resonances (“critical speeds”),

structural and other resonances, and changes in machine load or other operating conditions.

The Trip Multiply function causes the monitor alarm setpoints (both Alert and Danger) to increase

by a fixed amount, either two times (2X) or three times (3X), according to the ordering option. Only

those monitors ordered with this option will be affected. The Trip Multiply function is performed in

the System Monitor, but is an ordering option for each monitor. It must be specified at the time of

order placement and be installed at the factory.

Trip Multiply is activated by contact closure on the PIM. A red LED on the System Monitor front

panel indicates that the Trip Multiply function is active.

MONITOR FUNCTIONS

SYSTEM POWER-UP INHIBIT

The System Monitor provides a Power-up Inhibit function. This function allows each monitor to

inhibit its alarms during power-up or whenever a system supply voltage falls below its operating

level. After power-up, the inhibit function remains active for approximately 2 seconds.

RACK INHIBIT

When activated by a external contact closure this function places all monitors in bypass, disables

all alarms, zero scales all outputs, and de-energizes the system OK relay. The connections for this

function are located on the power input module (PIM) at the rear of the rack.

SUPPLY VOLTAGES OK

Seven LEDs located behind the front panel of the System Monitor are ON to indicate the voltage

supplies are functioning. The voltage supplies are +VRH, +VRL, +7.5V, +5V, REF, -7.5V, and -VT.

There is a green LED (SUPPLIES OK) on the front panel of the System Monitor. When this LED is on

all of the voltage supplies are functional.

SYSTEM RESET

The System Monitor provides the ability to cause a System Reset. Closing external contacts

through terminals on the PIM or pressing the RESET switch on the front panel will cause a System

Reset.

Description

Relays are important to the integrity of monitoring systems. They provide

external alarm annunciation or input to an automatic shutdown device. You can

order 3300 monitors with quality, built-in relays. Installation requires no external

wiring between relays and rack, and no extra housing to mount the relays. This

facilitates installation and minimizes the chance of errors associated with field wiring.

The 3300 system offers 2 relay module types:

• Dual, with 2 relays per module

• Quad, with 4 relays per module.

For system installations on the machine deck, in hazardous areas, or in areas

with harsh environments, the dual relay module is available with hermeticallysealed relays.

For non-hazardous areas and clean environments such as control

rooms or instrument panels, modules with epoxy-sealed relays are available.

All relay modules include arc suppressors as a standard feature to increase the

life of the contacts by reducing arcing at the switching point.

Installation Checklist

Use the following items to plan a 3500 rack installation:

• What are the power requirements?

• Does the rack fit in the proposed location?

• Can you mount the rack in the proposed location?

• Does the proposed location provide enough air circulation?

• Does the rack require a weatherproof housing?

• What termination does the rack require (internal or external)?

• Does the rack require a telephone line?

• Does the location provide good grounding for the rack?

• If you plan to fit Internal Barriers, does the location provide an Intrinsically Safe Earth?

Weatherproof Housing Installation

This section describes the 3500 weatherproof housing and provides instructions for proper installation.

General Description

The 3500/06 weatherproof housing is an enclosure designed to meet NEMA 4 requirements and to contain

one 3500 series rack (rack mount option only). The housing design does not accommodate a Display Unit or VGA display.

The housing is available in painted steel or stainless steel versions, with or without conduit fittings, and with or without air purge accessories.

A hinged door provides access to the front of the rack. A bolt-on cover provides access to the rear of the rack.

General Installation Procedure

1. Review the Installation Checklist (see Section 3.2).

2. Install the Weatherproof Housing (if required) (see Section 3.3).

3. Install the rack (see Section 3.4).

4. Set the jumpers and switches on rack (see Section 3.8).

5. Install the External Termination Blocks (if required) (see Section 3.5).

6. Install the modules (see Section 4).

7. Wire the transducers, relay, and power to the rack and modules (see Section 3.9).

8. Perform the Software Portion of the Rack Installation (see Section 3.10).

Installation Checklist

Use the following items to plan a 3500 rack installation:

• What are the power requirements?

• Does the rack fit in the proposed location?

• Can you mount the rack in the proposed location?

• Does the proposed location provide enough air circulation?

• Does the rack require a weatherproof housing?

• What termination does the rack require (internal or external)?

• Does the rack require a telephone line?

• Does the location provide good grounding for the rack?

• If you plan to fit Internal Barriers, does the location provide an Intrinsically Safe Earth?

3500 Internal Barrier System Restrictions

• You must install 1 earthing module in each rack in the internal barrier system. 

The earthing module occupies 1 slot position in the rack when it uses Internal Barrier I/O modules.

• You must change the grounding configuration of the 3500/15 Power Supplies from the default factory setting.

See the 3500/15 Operation and Maintenance Manual (PN 129767-01) for instructions.

• You must isolate any RS-232 connection to any 3500 module. Monitors that support RS232 connections include Rack Interface Modules, 

Communication Gateways, and the 3500/95 PC Display. See the 3500/20 Operation and Maintenance Manual (PN 129768-01) for instructions.

This restriction does not apply to RS422 and RS485 connections to the rack. 

Monitors that support RS422 and/or RS485 connections include the 3500/20, 3500/90, 3500/92, 3500/93, and 3500/95.

• You must not use the 3500/94 VGA Display in internal barrier systems.

• You must not use bussed transducers, as internal barrier systems do not allow bussed transducers. See the TMR section of this manual for more information.

3500 Internal Barrier System Features

• The earthing module supports dual IS Earth connections for cables with cross-sectional areas up to 10 mm2. This module lets you test IS Earth continuity online.

• The design of the internal barrier I/O modules provides the 2 inches (50 mm) of separation required between safe and hazardous area field wiring.

• The connectors for safe areas and hazardous areas have different field wiring colors (green for safe and blue for hazardous) and connector pitches. 

This helps to avoid incorrect field wiring installation.

• Quick connect/disconnect connectors simplify field wiring installation and removal.

• You can locate standard and internal barrier I/O modules in the same 3500 rack. 

We recommend that you group the modules together as shown in Figure 2-10 to facilitate connection to field wiring.

To provide Intrinsically Safe (IS) vibration and process variable monitoring,

the 3500 system has a range of I/O modules with internal zener barriers.

When you install these modules in a 3500 rack with a 3500/04-01 Earthing Module, 

they provide an integrated solution for explosion protection for approved Bently Nevada

transducer systems that are located within all classifications of hazardous areas (surface industries other than mining).

3500 Internal Barrier System Restrictions

• You must install 1 earthing module in each rack in the internal barrier system. 

The earthing module occupies 1 slot position in the rack when it uses Internal Barrier I/O modules.

• You must change the grounding configuration of the 3500/15 Power Supplies from the default factory setting.

See the 3500/15 Operation and Maintenance Manual (PN 129767-01) for instructions.

• You must isolate any RS-232 connection to any 3500 module. Monitors that support RS232 connections include Rack Interface Modules, 

Communication Gateways, and the 3500/95 PC Display. See the 3500/20 Operation and Maintenance Manual (PN 129768-01) for instructions.

Multiple Output Interfaces

You can conveniently adjust monitor options (such as full scale ranges, transducer inputs,

recorder outputs, alarm time delays, alarm voting logic, and relay configuration) in the field via software.

Modular system design employs plug-in components which allow easy servicing and expansion.

The following three independent interfaces are available with the 3500 system:

• Data Manager Interface (Transient Data Interface External or Dynamic Data Interface External)

• Configuration/Data port

• Communications Gateway (support for Programmable Logic Controllers,

Process Control Computers, Distributed Control Systems, and PC-based Control Systems)

These interfaces allow you to easily view monitored parameters and their statuses in the following ways:

• System 1® Software

• Bently Nevada™ 3500 Operator Display Software

• Remote display panel

• DCS or PLC display

Convenient front panel coaxial connectors provide dynamic transducer signals

and allow you to connect diagnostic or predictive maintenance instruments.

Improved Integration to Plant Control Computer

The 3500 improves integration to the plant control computer with:

• Communication Gateways supporting multiple protocols

• Time synchronized vibration and process information

Reduced Installation and Maintenance Costs

The 3500 system provides the following cost-saving features:

• Reduced cabling costs

• Downward product compatibility

• Improved space utilization

• Easier configuration

• Reduced spare parts

• Improved serviceability

Improved Reliability

The 3500 offers several features to improve system reliability.

• Redundant power supplies available

• Triple Modular Redundant (TMR) monitors and relay cards available

Intrinsic Safety Option

If you wish to monitor equipment that is located in hazardous atmospheres,

the 3500 Monitoring System has a range of I/O modules with internal zener barriers.

These modules provide an Intrinsically Safe interface between the 3500

rack and the transducers located in the hazardous area.

3500 Monitoring System

The 3500 is a full-feature monitoring system whose design incorporates the latest in proven processor technology.

In addition to meeting the above stated criteria, the 3500 adds benefit in the following areas:

• Enhanced operator information

• Improved integration to plant control computer

• Reduced installation and maintenance cost

• Improved reliability

• Intrinsic Safety (IS) option

The following sections discuss these benefits in more detail.

Enhanced Operation Information

The 3500 design includes features to both enhance the operator’s information

and present this information so that the operator may easily interpret it.

These features include:

• Improved data set

– Overall amplitude

– Probe gap voltage

– 1X amplitude and phase

– 2X amplitude and phase

– Not 1X amplitude

• Windows®-based Operator Display Software

• Data displayed at multiple locations